Light Filtering Options: UV Filters

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Products to Filter Tungsten-Halogen Lamps (low temperature products)
METHOD	DESCRIPTION	ADVANTAGES/DISADVANTAGES	UV FILTRATION
Films	flexible sheets of polyester or acetate plastic with dispersed UV absorbers; pre-fabricated tubes or constructed by taping to itself with double sided tape unfiltered light at cathodes allowing generous overlap	inexpensive versatile difficult to use poor installation allows bleed of unfiltered light at cathode life expectancy unknown- minimum 5+ years	FAIR to GOOD (92­-99% UV excluded up to 400 nm) but varies among products and VARIABLE batch to batch
Sleeves	rigid acrylic or polycarbonate polymer with UV absorbing properties, or additives; molded into tubes that fit over the lamp with end caps to hold tube onto lamp	inexpensive long life - should last 10 years difficult to use easy to misplace end caps, allowing unfiltered light to bleed at cathodes heat build-up between lamp and tube can decrease life of lamp by 50% yellows with age affecting light quality	FAIR to GOOD (92-­98% UV excluded up to 400 nm) but varies among products and VARIABLE batch to batch - maximum life expectancy of 10 years
Coatings applied directly to lamp	fluorescent tube coated with plastic UV absorber that is baked on, becoming integral part of lamp	easy to use best UV filtration of products for fluorescent lamps good color rendering (88) less heat build-up than sleeves coated lamps are shatterproof other straight tube lamps can be coated relatively expensive coating may begin to fail in 3 to 4 years	EXCELLENT (100% to 288 nm and 99.8% up to 400 nm) recommended for 3-4 years, after which coating can fail at cathodes allowing unfiltered light to bleed
Isolating sheets of UV materials	UV filtering/absorbing glass or plastic sheeting material can be placed between lamps and artwork (glazing on framed works or as case construction material)	inexpensive can be easy to implement can be used between case and lights to block heat from lamps some products have yellow cast affecting quality of light assumes that all UV-sensitive materials are under cover melts or burns	FAIR to GOOD difficult to qualify due to several different products and due to possible application errors such as bleed around outer edges

Products to Filter Tungsten-Halogen Lamps (high temperature products)
METHOD	DESCRIPTION	ADVANTAGES/DISADVANTAGES	UV FILTRATION
Gel filters	thin flexible sheets that absorbs UV; can be cut to size and inserted into holders or clipped against fixture glass	inexpensive easy to use if fixture has a cover glass, filter holder or barn doors can be combined with filters to reduce heat or alter color life expectancy unknown but short - depends on heat exposure, wattage, placement custom holder must be made for many fixtures especially inexpensive systems yellows over time	FAIR (90% below 390 nm with some wavelengths transmitted in very harmful range between 300-350 nm) VARIABLE and UNCERTAIN life expectancy - replace every 1-2 years
Dichroic glass filters	glass with UV reflecting inorganic coating applied under vacuum, available in 2" and 4 3/4" and custom sizes	excellent UV filtration long-life imperceptible color distortion little heat build-up easy to use if fixture has a filter holder or clips relatively expensive scratching is difficult but effects UV blocking characteristics custom holder must be made for m any types of fixtures especially less expensive halogen systems yellows over time	EXCELLENT (100% UV excluded below 380 nm -1% below 400 nm)
Isolating sheets of UV materials	UV filtering/absorbing glass or plastic sheeting material can be placed between lamps and artwork (glazing on framed works or as case construction material)	inexpensive can be easy to implement by placing between case and lights cannot be used in close proximity to tungsten lamps due to heat some products have yellow cast affecting quality of light assumes that all UV-sensitive mate rials are under c over cannot be used in all situations - such as framing pastels melts or burns	FAIR to GOOD depending on product chosen and on implementation

Products to Filter Architectural Glazing and Case Construction
METHOD	DESCRIPTION	ADVANTAGES/DISADVANTAGES	UV FILTRATION
Sheet films or varnishes	sheets or varnishes containing UV absorbers or reflectors applied to interior or exterior of existing building glass by a dealer	moderately expensive can be "invisible" some products can also reduce infrared heat and visible light can reduce glare improves shatterproof quality must be well-applied for maximum benefit scratching affects UV blocking characteristics life expectancy of 5 years then must be removed and reapplied can be difficult to remove - poor workmanship can damage historic fabric of building aged products c rack, peel and shrink	FAIR to GOOD (from 82% up to 99% UV excluded up to 400 nm) varies among products and VARIABLE batch to batch- review highest percentage of transmission as well as average - should last for approximately 5 years
Acrylic plastic sheet	rigid acrylic sheet with UV block dispersed throughout the plastic that can be used as internal storms or as panels hung at windows; also used in the construction of cases and framing of art works	relatively inexpensive long life up to 15 years scratching does not affect UV filter characteristics cuts as other plastic sheet mate rials used in exhibition construction can be used to construct a case or placed between case and lights to block UV and heat generate d by lamps shatter proof cannot be used in close proximity to tungsten l amps due to heat many products have yellow cast affecting quality of light cannot be used in some situations- such as framing pastels melts or burns	FAIR to GOOD (from 80% to 98% UV excluded up to 400 nm) varies depending on product, lasting up to 15 years